Globally, there is an increasing level of funding targeted to pay farmers and rural communities for the provision of ecosystem services, for example through Payments for Ecosystem or Environmental Services (PES) schemes and pilots for Reducing Emissions from Deforestation and forest Degradation, and maintaining or enhancing forest carbon stocks (REDD +). Therefore, there is growing interest in understanding the effects of economic incentives on participants' behavior and motivations. We adopt here an innovative research design to test for motivational crowding effects through a forest conservation game in Colombia's Amazon Piedmont, using individual, collective and crop-price premium economic incentives. We implement a post-experiment survey on different types of motivations based on Self-Determination Theory (SDT) to test for changes in motivations. Our findings show that all types of PES, except for the crop-price premium payment, increased conservation behavior in the experiment. However, not all types of payments affected motivations equally: collective payments enhanced social motivations to protect forests and the crop-price premium reduced intrinsic and guilt/regret related motivations. These findings contribute to disentangling the interaction between incentives, motivations and behaviors in a context of agricultural expansion and growing concern for forest conservation.